Antenna arrays are widely used for communication and sensing in a variety of environments. Some of the environments, such as military shipboard use, are extremely harsh, in that the antenna arrays are subject to mechanical stress attributable to wind and high waves, and the corrosion attendant on a salt-water environment. Additionally, some antenna arrays may be expected to continue operation notwithstanding blast and radiation effects stemming from common or nuclear explosions.
Moreover, with communications and sensing becoming increasingly important, vehicles and communication sites carry many antennas, for covering various bands of frequencies, and for generating various different beam patterns. The proliferation of different antennas at a single site or installation tends to degrade the environment for the other antennas, making it more difficult to achieve the desired performance. For this reason, "broadband" antennas, which can cover broad bands of frequencies, are desired. However, it is difficult to achieve broad bandwidth from an antenna element, and especially so in the context of an antenna array.
Vivaldi and tapered notch antennas have been shown to have a bandwidth approaching 5:1 in an array context. However, these antennas are difficult to harden against the elements and blast overpressure.
Improved broadband, hardened antenna elements, suitable for use in a hardened antenna array, are desired.